For years people like me have carped that not only is the public cloud a small slice of IT spending, but the big public clouds are also much more likely to attract startups or other digital natives as customers instead of conventional enterprises.

That begs an important question: What then exactly is the “enterprise cloud”? Recently I interviewed Bob Weiler, executive vice president of global business units at Oracle, to drill into that topic. As head of Oracle Industries, it’s his job to marshal Oracle’s full portfolio of technologies to serve seven key verticals — and Oracle’s cloud is a big part of that push.

When Oracle says “cloud,” one of the first things to remember is that most of the company’s cloud revenue comes from SaaS, despite Larry Ellison’s big talk about going head-to-head against AWS in full-on IaaS combat. SaaS makes particular sense in serving vertical industries. Through acquisition and internal development, Oracle has acquired the expertise to serve, say, the utilities or pharmaceutical or financial services industries through vertical SaaS applications.

Weiler says that Oracle’s most successful acquisitions have been vertical vendors that began life as SaaS plays:

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Again, this is a very different play than what AWS, Azure, or Google Cloud do. They’re essentially multitenanted self-service offerings; arguably, multitenancy and self-service define the cloud. Oracle, on the other hand, leans toward a have-it-your-way approach. Whether SaaS, PaaS, or IaaS, Oracle offers not only multitenancy but also single-tenancy and managed cloud services across its entire portfolio — as well as, in many cases, on-premises versions. Rather than click choices on an AWS menu to fire up a new project, you call Oracle sales and work out your special deal.

As a sales and marketing organization, that’s what Oracle does. But that’s also the nature of the enterprise cloud: Regulatory constraints and sheer complexity loom large and demand special treatment. As Weiler says, “If I have an application that is a deposit application at a bank, that’s not going in a multitenancy cloud, or we have a problem — but maybe an analytics application or maybe a lending or leasing application or maybe a customer origination application, well, that’s OK.”